A simple and robust self-reset image sensor design using Schmitt trigger circuit is presented. Offset and reset delay accumulations are compensated effectively so that a self-reset CMOS image sensor can exploit signal-to-noise ratio (SNR) improvement along with its wide dynamic range under multiple resets. It has been designed and simulated using 0.18 mum CMOS technology to show SNR improvement of 22.8 dB with 1000 self-resets. It also provides low power consumption and fewer components for pixel-level image sensor design.